Knee Cap DislocationDislocated patella or popping patella
Perth knee surgeon | Orthopaedic surgeon Dr David Colvin - shoulder and knee surgery
Dislocated knee capKnee surgeon perth
What is a knee cap dislocation?
Knee cap dislocation, also known as patella dislocation, occurs when the knee cap is completely displaced out of its normal position. The knee cap runs in a groove on the front of the femur, called the trochlea.
When the knee cap is knocked out of this groove, a dislocated patella always goes to the outer (lateral) side of the knee. As a result, the muscles on the inner side of the knee are damaged and the ligaments can be torn or stretched.
About Dr Colvin
Dr. David Colvin, trained in orthopaedic surgery in Perth. David's specialty is knee and shoulder surgery and sports injuries.
What causes knee cap dislocation?
Patella dislocation is caused by a direct blow to the front of the knee or from a sudden pivoting of the leg, forcing the knee cap to the outside. Some people are more at risk of patella dislocation. Risk factors include:
- Maltracking or tilt of the patella.
- Being generally loose jointed.
- Being knock kneed.
- Having a high knee cap.
- Being born with a shallow groove for the knee cap (shallow trochlea).
Patella maltracking is a very common problem. Even a normal knee cap has a tendency to run towards the outer half of the groove. In some people this can be quite severe, resulting in maltracking and patella tilt. Sometimes the patella does not completely dislocate. It may feel like it is partly slipping out, which is called patella subluxation.
What are the symptoms of knee cap dislocation?
A knee cap dislocation is a very dramatic event which causes sudden severe pain and an inability to straighten the knee.
Usually the knee cap is visible sitting in a very abnormal position on the outer half of the knee. If you straighten the knee, the patella may come back into its normal position with a sudden clunk.
A small number of people dislocate their patella and it comes back into position immediately. They may not even be aware that the knee cap was dislocated briefly. It may be necessary to go to hospital to have the knee cap put back into place.
Even once it’s back in place, the knee usually becomes very sore and swollen over the following days.
Some people experience patella subluxation where it partially dislocates and then comes back into position spontaneously. This can be very unnerving and the knee can feel like it’s going to give way
In the field of shoulder and knee reconstruction, successful outcomes from an operation are 50% surgery and 50% rehabilitation. You could say the surgery is the easy bit, the rehabilitation is all hard slog. Dr Colvin’s CO.RE exercise programs are just that, a core plan for your successful recovery.
Orthopaedic surgery for knee cap dislocation
Repeated patella dislocation or subluxation usually requires patellofemoral reconstruction surgery. There are two treatments for this type of knee injury.
Dr Colvin may recommend a Tibial Tubercle Transfer (TTT or Triple T). This involves cutting and shifting the bone where the patellar tendon attaches to the tibia, to centralise the knee cap.
The alternative procedure is called a Medial Patellofemoral Ligament Reconstruction (MPFL Reconstruction). This reconstructs the torn ligaments on the inner half of the knee that hold the patella in place. In some cases, both procedures are performed at the same time.
Dislocating knee cap? Make an appointment for advice
Tibial Tubercle Transfer
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(08) 9489 8787
Suite 213/25 McCourt St,
Subiaco WA 6008
Dr David Colvin consults at:
Western Orthopaedic Clinic
- These rooms are part of St John of God Subiaco Hospital.
- Parking is available on site.
Dr David Colvin operates at:
St John of God Subiaco Hospital
12 Salvado Rd,
Subiaco WA 6008